Patient Assessment and Preparation
Purpose of pre-test assessment
Pre-test assessment decides whether a test is safe, whether results will be valid, and which reference values apply. Know the indications (dyspnea, cough, known or suspected asthma, COPD, or interstitial disease, pre-operative evaluation, disability evaluation, monitoring therapy) and the absolute contraindications to spirometry: recent myocardial infarction, unstable angina, recent pneumothorax, active hemoptysis, recent thoracic, abdominal, or ocular surgery, cerebral aneurysm, and acute illness such as vomiting. DLCO adds caution after recent MI or with unstable cardiovascular status.
Medications and behaviors
Record all medications and hold bronchodilators per protocol: short-acting beta agonists roughly 4 to 6 hours, long-acting beta agonists and long-acting anticholinergics 12 to 24 hours, and combination inhalers according to the longest-acting component. Avoid smoking or vaping for at least 1 hour, vigorous exercise for 30 minutes, and a heavy meal before testing. Note oxygen use, and for DLCO record the prescribed FiO2, because supplemental oxygen alters the measurement.
Data that must be captured
Height, weight, age, sex, and ethnicity are required for GLI-2012 reference equations; omitting ethnicity is a common error that shifts predicted values. Record baseline SpO2, heart rate, blood pressure, respiratory rate, and the patient understanding of instructions.
Worked example
A 58-year-old with asthma on a long-acting beta agonist plus inhaled corticosteroid arrives at 09:00 having taken the inhaler at 08:00. Do not treat this as a baseline spirometry: reschedule, or document the recent dose, because bronchodilation will inflate FEV1 and can mask obstruction.